1. Field of the Invention
The present invention relates to an improved device of balancing lever in a multiplicative key.
2. Description of Related Art
Conventional slim keyboards of notebook computers use keys, which each have a top, a base and a support device in between. The support device is shaped like a bridge or like a pair of scissors. Bridge-like supporting devices have been disclosed in Taiwan Patent Publication No. 282857 entitled "Key system for keyboard", No. 286794 entitled "Key switch", and No. 319438 entitled "Key switch with scissors-like lever element". The disclosed conventional systems are best suited for square-shaped keys of regular size. Elongated keys or so called multiplicative keys, e.g. the special keys SPACE, SHIFT, ENTER, require inserting a balancing lever. If no balancing lever is inserted, pressing an elongated key outside the center thereof will incline the key, and the key will not work properly. The balancing lever prevents tilting of the elongated key. But, during fast typing, conventional balancing levers are not able completely to prevent inclined elongated keys, which leads to extra noise and awkward typing. To improve on this shortcoming, Taiwan patent publication No. 346213 entitled "Improved enlarged key device" has disclosed a balancing lever which has two ends with an elastic tube each. The elastic tubes do not allow a horizontal movement of the top of the key against the base thereof. However, the device disclosed not only needs mounting additional elastic tubes, requiring extra cost and assembly time, but also is subject to fatigue. A worn elastic tube does not ensure the elongated key to be pressed down without tilting and is not easy to replace, such that typing remains impaired. To overcome this deficiency, the present invention further improves the structure and usability of elongated keys.